1. Field of the Invention
The present invention relates to blowout preventer drip trays in the field of hydrocarbon drilling rigs. More particularly, the invention relates to annular bop trays of the type that are installed around a wellhead stem pipe above the high drill of its blowout preventer, to catch and contain liquids, as are useful for environmental containment and/or re-use of liquids that leak from or are applied to the wellhead, or that otherwise spill from and around the wellhead.
2. Description of Related Art
A blowout preventer drip tray—a “bop tray”—is a liquid containment tray that has been used for several decades in oilfield drilling, production and work-out. Bop trays are mounted around the wellhead stem pipe beneath the blowout preventers. Largely for environmental purposes, they function to catch and contain potentially hazardous oilfield liquids spilling from the wellhead. As is fairly well-known, liquid spills on the ground around a wellhead can be expensive to clean up.
Structurally, the basic part of a conventional bop tray is a circular pan, with an up-turned circumferential rim to help contain the captured liquids. The trays typically have a central hole through which the wellhead stem pipe extends, and they often mount above or below one or more wellhead collars and/or flanges that are connected to the wellhead stem pipe. One popular bop tray is marketed as the “Katch Kan,” versions of which have been commercially available since the early-to-mid-1990's.
For ease of installation, conventional bop trays come in two, substantially-symmetrical, semicircular halves. The two halves are positioned on horizontally opposite sides of the wellhead and then bolted together around the wellhead to catch and contain liquids. Such conventional bop tray designs serve the basic functions reasonably well, but it is accepted that it takes up to an hour or so to properly install conventional bop trays. Not only is there a labor and work stoppage expense associated with the amount of time required, but usually the need to catch the liquids is imminent when the bop tray is being installed, which increases the risk of a worsening clean-up problem while the crew is installing the bop tray.
Additionally, currently available containment trays suffer from a significant limitation in that the amount of pressure which may be exerted on the combined halves and on the well head section enclosed is limited by the bolt type fasteners used to secure the two halves together.
The liquids caught by bop trays might include everything from leaking oil to cleaning solutions, as well as drilling mud, brine and other hydraulic fluids, most of which are both potentially hazardous as well as costly. Remediation/clean-up expenses and environmental impacts of inadequate containment of the liquids can be enormous. Moreover, when the spilled liquids are valuable, bop trays also allow for capture, sale and/or re-use of the liquids that leak from or are applied to the wellhead. Only a little liquid might spill during each drill string connection, but the cumulative costs of spilled liquids can be substantial over the duration of a drilling operation. Accordingly, many bop trays are provided with slots or holes to accommodate surrounding structures, such as hoses to recirculate the liquids or to direct the captured liquids into appropriate tanks.
Irrespective of the detailed approaches of the prior art, there remains a long-felt need to better capture, contain and manage liquids spilling around a wellhead. Moreover, with bop trays specifically, there has been a long-felt need for a bop tray that is both highly functional and dependable while also being faster and easier to install and use, yet oilfield tool manufacturers and support services have not been able to adequately address such needs.